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Production of moldable bone substitute

a bone substitute and moldable technology, applied in the field of composites, can solve the problems of insufficient standard bone fracture treatment, damage to bone tissue, and inability of the body to heal by itself, and achieve the effects of controlling the hardening speed of the composite, long shapeability time, and high final strength

Inactive Publication Date: 2010-09-09
PROMIMIC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0019]A primary object of the present invention is to provide a composite, serving as a scaffold for bone cell growth, comprising of nanocrystalline HA, a plasticizer and a biodegradable polymer. Another object is to provide a method of controlling the hardening speed of the composite by addition of specific biodegradable plasticizers to provide a composite with a long shapeability time and a high final strength.

Problems solved by technology

Physical trauma, such as fractures, may damage the bone tissue in such complex ways, which makes standard bone fracture treatments insufficient.
Tumours, which destroy large portions of bone tissue, can make it impossible for the body to heal the injury by itself.
Powder based products are successful in restoring bone tissue, but are less suitable for load-bearing applications.
One disadvantage is the brittleness of the structure, due to the fact that the material contains no substances, such as polymers, which may dissipate forces applied to the material, as in natural bone.
Another disadvantage is that the material requires careful fitting before it can be inserted in the body.
However, these composites are generally too stiff to be shaped at room temperature.
Dense composites have high strengths but are lacking in osseointegration properties since the bone cells have less surface area to grow on.
However, even though U.S. Pat. No. 7,186,759 discloses a composite that contains a porogen in the form of a water-soluble or hydrolytically degrading polymer, the mouldability has proven to be restricted to a short period of time.

Method used

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  • Production of moldable bone substitute
  • Production of moldable bone substitute
  • Production of moldable bone substitute

Examples

Experimental program
Comparison scheme
Effect test

example 1

Synthesis of Nanocrystalline Hydroxyapatite Gel

[0069]2.82 g of CaO was mixed with 150 ml of H2O in a beaker. The dispersion was allowed to stir for 1 hour. In a separate beaker, 3.45 g of H3PO4 (85 wt %) was mixed with 150 ml of H2O. The contents in the two beakers were mixed at ambient temperature, and the resulting gel was allowed to stir for 12 hours. The mixture was filtered in a grade 4 glass filter and washed extensively with water (2.5 L). A portion of the gel was dried and analyzed with XRD and nitrogen adsorption. The specific surface area, as calculated with the BET method, of this sample was found to be 200 m2 / g.

example 2

Synthesis of Nanocrystalline Hydroxyapatite Gel with Amino Acids

[0070]The nanocrystalline hydroxyapatite was prepared as follows. 6.70 g of L-Aspartic acid was mixed with 150 ml H2O in a beaker. 2.82 g of CaO was added to this solution, and the mixture was allowed to stir for 1 hour. In a separate beaker, 3.45 g H3PO4 (85 wt %), 6.65 g L-Lysine and 150 ml H2O was mixed. The pH of this solution was 6.46. The contents in the two beakers were mixed at ambient temperature, and the pH was measured to 8.10. The mixture was allowed to stir for 12 hours. The mixture was filtered in a grade 4 glass filter and washed extensively with water (2.5 L) to remove excess amino acids. The pH of the resulting gel was measured to 7.90.

[0071]A portion of the gel was dried and analyzed with XRD and nitrogen adsorption. The X-ray diffractogram is shown in FIG. 1. The specific surface area, as calculated with the BET method, of this sample was found to be 210 m2 / g.

example 3

PCL / Tocopherol / HA

[0072]HA gel was prepared according to Example 1 or 2. The gel, consisting of coated hydroxyapatite particles and water, was mixed with 6 grams of poly(caprolactone) with a molecular weight of 80000 g / mol, and 6 grams of tocopherol. The mixture was heated to 70° C. under extensive stirring until complete evaporation of the water had occurred. The yellow colored mixture was removed from the stirring equipment and allowed to cool to room temperature. The composite was readily moldable for approximately 45 minutes, during which the compressive strength was found to be below 4 MPa. The maximum compressive strength of 6.7 MPa was reached after roughly 120 minutes.

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Abstract

Composites and methods of producing a mouldable bone substitute are described. A scaffold for bone growth comprises nanocrystalline hydroxyapatite (HA), a bioresorbable plasticizer, and a biodegradable polymer. Plasticizers of the invention include oleic acid, tocopherol, eugenol, 1,2,3-triacetoxypropane, monoolein, and octyl-beta-D-glucopyranoside. Polymers of the invention include poly(caprolactone), poly(D,L-Lactic acid), and poly(glycolide-co lactide). Methods of regulating porosity, hardening speed, and shapeability are also described. Composites and methods are described using nanocrystalline HA produced with and without amino acids. The scaffold for bone growth described herein displays increased strength and shapeability.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Application Ser. No. 61 / 209,385 filed Mar. 6, 2009.FIELD OF THE INVENTION[0002]The present invention relates generally to a composite, serving as a scaffold for bone cell growth, comprised of nanocrystalline hydroxyapatite (“HA”), a plasticizer and a biodegradable polymer. Certain embodiments of the invention, not intending to be limiting, are disclosed. In one embodiment of the invention a method is provided for controlling the hardening speed of the composite by addition of specific biodegradable plasticizers resulting in a composite with a prolonged shapeability time and a high final strength.BACKGROUND OF THE INVENTION[0003]In medicine, there are many situations where it is necessary to aid the human body to build new bone. Physical trauma, such as fractures, may damage the bone tissue in such complex ways, which makes standard bone fracture treatments insufficient. Tumours, which...

Claims

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Application Information

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IPC IPC(8): A61K9/00C12N5/071A61P19/00
CPCA61L27/46A61L27/58A61K33/42A61L2400/12C08L67/04A61P19/00A61L27/54A61L27/28A61L27/502A61L2430/02
Inventor KJELLIN, PERHANDA, PAUL
Owner PROMIMIC
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